1. Field of the Invention
The present invention relates to a head slider for a disk apparatus, or in particular, to a head slider for a disk apparatus comprising a magnetic element adapted to fly over a magnetic recording medium of a disk type to record or reproduce magnetic information between the magnetic element and the magnetic recording medium, wherein the surface of the head slider opposed to the medium is formed with, with respect to the direction in which the medium runs, an inflow pad portion at the upstream end and a pair of side rail portions extending downstream from the inflow pad portion, and a center pad at the central part and a pair of side pads on the sides of the center pad and upstream of the center pad at the downstream end of the head slider.
2. Description of the Related Art
First, a conventional disk apparatus having a magnetic slide header mounted thereon is explained with reference to FIG. 15. FIG. 15 is a plan view of the conventional magnetic disk apparatus 1, in which one or a plurality of disk-type magnetic recording media 3 are mounted on a rotatable spindle at predetermined intervals.
A head slider 10 is arranged for each of the obverse and reverse surfaces of each rotary magnetic recording medium 3, and each is supported through a suspension 5 at the end portion of an arm 4 of an actuator swingably supported on a pivot. The head slider 10 is adapted to be moved, in radial direction (for a seek operation) on each medium surface, by a voice coil motor 6.
The head slider 10 of the disk apparatus 1 having the structure described above, as shown in FIG. 16, moves outward or inward substantially radially on the disk-type recording medium while flying over the medium surface under a positive or negative pressure generated by the disk-type recording medium 3 rotating at high speed.
In FIG. 16, with the high-speed rotation of the magnetic recording medium 3 in the direction along arrow P, an air stream as shown is generated in the direction of the arrow P between the magnetic recording medium 3 and the head slider 10. Through this air film, under positive or negative pressure, the head slider 10 flies at a predetermined height from the surface of the magnetic recording medium 3 and is kept in predetermined spaced relation with the surface of the recording medium 3.
In order to realize the high-density packaging of the magnetic recording medium 3, the head slider 10 is desirably placed as near to the disk-type recording medium 3 as possible. Under various conditions, however, a predetermined interval is desirably maintained between the medium surface and the head slider. If the total length of the head slider 10 is 1.25 nm, the flying height t of the head slider 10 from the medium surface is tens and several nm or about 15 nm from the nearest portion of the medium surface where the recording/reproducing magnetic element 7 is mounted.
The head slider 10 of the disk apparatus, having the above-mentioned structure, flies over the medium surface due to the force generated by the disk-type recording medium 3 rotating at high speed in the direction of the arrow P in FIG. 17, while at the same time moving (the seek operation) outward or inward substantially radially over the disk-type recording medium.
As a result, the running speed of the disk-type recording medium 3 relative to the head slider 10 varies depending on whether the head slider 10 runs along the inner peripheral side, the middle peripheral side or the outer peripheral side of the disk-type recording medium 3. At the same time, the direction in which the disk recording medium 3 runs with respect to the head slider 3, i.e. the velocity vectors V1, V2, V3 and the directions thereof are varied. Specifically, between the innermost periphery and the outermost periphery, the running speed changes about twice and the speed vector changes about 25 degrees.
In designing the head slider 10 of the disk apparatus, therefore, it is important to maintain as uniform a flying height t (FIG. 16) of the head slider as possible over the whole periphery of the disk-type recording medium 3 and even allowing for a change in velocity or a change in the velocity vector.
In similar fashion, in the case where the arm 4 (FIG. 15) of the actuator supporting the head slider 10 performs the seek operation, the head slider 10 mounted at the forward end of the arm 4 moves radially inward at some timer and outward at other of the disk-type recording medium 3. In the process, the addition of the seek operation to the velocity vector of the head slider 10 with respect to the recording medium 3 changes the direction of the velocity vector (V4 or V5) by about 15 degrees.
With this direction change of the air flow, therefore, the flying height of the head slider, above the recording medium, is required to be maintained as uniform as possible.
Further, the device carrying the magnetic disk apparatus, whether it is a stationary computer or a mobile personal computer, is required to with stand operating conditions including a low atmospheric pressure. Generally, the HDD (hard disk drive) requires that the use at high altitudes is taken into account and therefore has to be operatively guaranteed even at an altitude of, say, 3000 m above sea level.
Furthermore, taking manufacturing problems such as machining errors and assembly errors into consideration, a robust design is required.
Of all the design problems of the head slider of the disk apparatus described above, this invention is especially intended to provide a head slider for the disk apparatus usable under low atmospheric pressure.
Specifically, the head slider of the conventional disk apparatus poses the problem that the flying height of the head slider decreases with low atmospheric pressure. Especially in the case where the head slider supported at the free end of the arm of the actuator is located on the inner side (inner side) of the disk medium while performing the seek operation radially of the rotating disk medium, the peripheral speed of the disk-type recording medium relative to the head slider is so low that a sufficient air-bearing pressure cannot be secured for the head slider. As a result, the flying height decreases considerably with a decrease in atmospheric pressure.
An attempt to secure a head slider having little dependency on the atmospheric pressure, i.e. having a characteristic robust against low atmospheric pressure encounters the problem of a decreased robustness against a change in peripheral speed. Also, with the decrease in atmospheric pressure, “the pitch angle”, providing an inclination angle of the rotating head slider with respect to the direction upstream or downstream of the medium, decreases, as does the flying height of the head slider.
The conventional technique disclosed in Japanese Unexamined Patent Publication No. 2003-323706 related to this invention proposes a magnetic head in which the magnetic core is prevented from coming into contact with the magnetic recording medium by decreasing the effect of the atmospheric pressure on the spacing between the magnetic core and the magnetic recording medium in the case where the slider body flies over the magnetic recording medium.
JP-A 2003-323706 disclosed a head slider of a magnetic recording apparatus, wherein the center pad portion having the magnetic core is formed at the central part of the outflow end (trailing end portion) of the surface of the slider body opposed to the medium, and side pad portions are formed at the transverse end portions nearer to the inflow end (leading end) than the center pad portion. The total area of the surfaces of the two side pad portions opposed to the medium is larger than the area of the surface of the center pad portion opposed to the medium. Each pad portion is formed with a front stepped surface lower than the other parts on the leading side.
As described above, an attempt has been made to improved the robustness of the magnetic head slider against the variations in the atmospheric pressure by adjusting the area of the surfaces of the center pad portion and the side pad portion opposed to the medium. The method disclosed in patent reference 1, however, takes into consideration only the areas of the surface of the center pad portion and the side pad portions in opposed relation to the medium, and fails to sufficiently take into account the amount of the pressure generated by the center pad and the side pads.
In view of this, according to this invention, regardless of the area of the surface of the center pad portion and the side pad portions opposed to the medium, the positive pressure generated in the side pad portions is increased beyond the positive pressure generated in the center pad portion thereby to secure the robustness against the variations in the atmospheric pressure. Further, the robustness against the greater variations in the atmospheric pressure can be improved further by designing the shape of the side pad portion appropriately.